By Angela Canterbury On July 14, the U.S. and its international negotiating partners finalized a strong, verifiable agreement to prevent a nuclear-armed Iran. Tough and principled diplomacy resulted in a very good deal that will block any pathway Iran might have to a nuclear weapon for many years to come.

But now it is in the hands of Congress.

Earlier this year, Congress passed legislation that gives it 60 days to review the deal. Unlike the 165 Republicans who opposed the accord before it was even submitted to Congress, other lawmakers ought to closely examine the deal. In doing so, they should rely on arms control and nuclear nonproliferation experts.

What’s in the agreement? Iran made extensive concessions, including the dismantlement of most of its nuclear infrastructure. They forfeit two-thirds of their centrifuges and 98 percent of its uranium stock. They will not produce weapons-grade plutonium and will not possess uranium with more than 3.67 percent enrichment (weapons grade uranium is 90 percent).

Moreover, the accord is supported by national security experts, former diplomats and the American people — not because they trust Iran — they don’t. And neither does President Obama — nor do any of his P5+1 negotiating partners from Britain, France, Germany, Russia and China. That’s why this is a “don’t trust, verify” deal. It includes the most rigorous and intrusive inspection regime ever negotiated.

What did Iran get? Relief from the harsh economic sanctions imposed by the U.S. and other world powers over the past decade for their suspected nuclear weapons activity. This relief will only come after the International Atomic Energy Agency has verified Iranian compliance.

If the Iranians cheat, we’ll know it. Then the economic sanctions will snap back into place. Of course, we’ll also still have the military option — and it will be more effective, given what we will have learned about Iran as the result of the access this agreement provides.

Critics have said we could have gotten a better deal. But they have not articulated any acceptable alternative — nor is there any. A better deal is a utopian fantasy. And if Congress rejects this deal, the sanctions regime will fall apart, giving Iran both an economic boost and the ability to build a bomb unfettered in the shadows. In fact, the most realistic alternative to this very good deal is war.

The wars we’ve been waging for the past 13 years would pale in comparison to a war with Iran, which would do far more to imperil our allies Israel and Saudi Arabia than the remote likelihood that Iran will resume a nuclear weapons program under this deal. And, by the way, top military experts will tell you — we cannot bomb Iran’s nuclear program out of existence.

This deal is the best option: It prevents both a nuclear-armed Iran and another war and therefore makes the U.S. and the world far safer.

And so, members of Congress will soon face two of the most critical votes of their careers. Republican leaders are gunning to pass a resolution of disapproval — and they’ll likely succeed. Then they will seek to override President Barack Obama’s veto. But, the Republicans will need two-thirds of Congress to do it — and this is where the deal can and must be defended.

But it won’t be easy, since billionaire Republican Sheldon Adelson and other big money donors are pouring millions into an effort to kill the deal. One of the most powerful lobby groups in Washington—the Netanyahu-aligned American Israel Public Affairs Committee—is leaning hard on Democrats who have gotten used to AIPAC support for their elections. Not surprisingly, many of the most vocal critics are the same war hawks who drove us into Iraq.

This moment rivals that fateful vote cast in favor of the Iraq War in 2002 — a vote that has been recalled by many with deep regret. In addition to wealthy special interests, lawmakers will also be hearing from everyday American people — the majority of whom support the deal — and hopefully lawmakers will listen to them, as well as to their own conscience. Each member of Congress should ask: What will my great-grandchildren say about these votes?

This agreement is about the U.S. leading on global and national security in way that truly makes us safer instead of miring us in war. A vote on the Iran deal is truly a vote for war or peace. Which side of history will Congress be on?